Hi,

Could anyone help diagnose my lights issue?

1- Brake lights work
2- Tail lights do not work even when headlights are on (dangerous at night)
3- headlights work (see pic)
4- Side running lights work in front, but not when headlights are on (see pic)
5- License plate lights do not work (but I haven't checked bulbs yet)
6- Reverse lights work
7- Turn signals work

So the main problem is the tail lights and running lights. I tried to change the bulb in the tail light (#7443) but it turned out to be an LED assembly (see pic)

It does not appear that the 10A fuse under the steering wheel (position #43) or the 10A fuse under the hood (position #3) are burnt.

Thanks!

Attached Images

       

possible "tail" fuse inside interior fuse box

Try either testing the 10amp fuses with a multi-meter or swapping them with a known good fuse, sometime a fuse can be burnt out but not visually apparent.

Thanks, I will get a new fuse and try that soon.

Just a quick follow up...I removed the wiring harness from the tail light assembly and put a 7443 light bulb into the wiring from the front of the vehicle. The brakes lit the bulb up, but the bulb did not light up when the headlights were on.

Thanks

Update:

- Headlights work
- Turn signals work
- Reverse lights work
- Brake lights work
- Tail lights DO NOT work
- License plate lights DO NOT work
- Instrument cluster lights work

I plugged new bulbs (#7443) into the wiring connectors and the same issues so I think the (LED) tail light assembly can be ruled out. I also plugged new light bulbs into the license plate lights and they still did not work.

I tested the fuses with a circuit test light and found the following:

- 10A STOP fuse (under the hood) appears to be good. (See pic)
- 10A TAIL fuse under the dash does NOT appear to be good, but replaced with another (good) fuse and it still did not work. (See pic)
- The contacts under the fuse (with fuse removed) are NOT working either (see pic)

I'm not sure why the instrument panel lights are working since it appears to run through this fuse? (See pic of fuse items #43).

Any ideas of what I can check next or mistakes I've made so far?

I really need to get this figured out so my son can drive this at night without getting run in to.

Thanks in advance for your help!

Attached Images

         

for the tail fuse, the lights have to be on first to test.

also was anything else installed? you might want to swap some relays around.

I started the 4runner and turned the lights on to test the fuse and fuse block but no power for that tail 10A fuse area.

Also it's a (new to me) vehicle, but I'm not sure if anything else being installed recently (but everything appears to be stock).

Thanks!

Well, I tried a new headlight control switch (stalk) but it didn't solve the issue. I still have brake lights/turn signals/reverse lights but NO tail lights or parking lights.

I've tried bulbs, I've tested fuses and even replaced a 40A trailer fuse under the hood because I couldn't figure out how to test those square type ones. I still suspect an issue in the 10A tail fuse area (#43 position on the chart) in the interior fuse block (not the fuse itself which tests fine) but why would the instrument panel lights, fuel injection etc still work since it's on that fuse as well? When I take that fuse out and use the test light where the fuse plugs in it doesn't seem to have power.

Is there a tail light relay I can check or any other ideas?

​​​​​​​Thanks

It was the tail light relay which is hidden on the back of the interior fuse block assembly. The lower dash area had to be taken apart and the fuse box dropped in order to access it.

thats good you found it.

Thanks for posting the solution. It will help someone else later, I'm sure, maybe me.

Hi Everyone,

I have the same problem as described in the original post. I have a 2005 Toyota 4 Runner V8 Limited with 4WD.

I have changed all the fuses, associated relay behind the fuse box in the interior, turn signal (head lamp) switch, all the tail light bulbs and even the entire rear tail light assemblies and still no luck.

I have brake lights, turn signals, headlights, fog lights, reverse lights, but no rear running lights.

Please help, I am stumped and don't know what else to try. Thank you in advance!!!

~Carter

Have you check the fuse box under the hood?

Yes, I replaced all the fuses in the engine compartment as well just to rule that out.